Numerical Modeling of Flow around Bridge Abutments in Compound Channel

Numerical modeling of flow around bridge abutments located on the floodplain of a compound open channel is presented using a two-dimensional, depth-averaged, k-ε turbulence model. The model uses a finite volume difference scheme with a staggered grid to solve the governing equations of flow and turbulence transport in elliptic form. The numerical model results for velocity and flow depth are compared with laboratory data for flow in a compound open channel that consists of a main channel and symmetric floodplains set at a fixed bed slope. Reasonable agreement between the numerical results and experimental data is shown both for the case of steady, uniform flow and for the case of steady, nonuniform flow around a bridge abutment located in the floodplain. The numerical results are applied in a correlation of measured values of equilibrium clear-water scour depth with numerical values of local velocity near the upstream corner of the abutment face. This study is limited to shallow flow in a laboratory compound channel with wide, rough floodplains and vertical-wall abutments that end in the floodplain.